Water

Water for a foreigner in Peru is often a challenge, especially for a family with kids.  You DO NOT want your kids to get sick, if at all possible, from water contamination!  Bottled water is usually available in most places, even in rural communities far from the beaten path.  Our preferred brands, in order, are San Luis, San Carlos, San Mateo, Cielo, and then the other brands.

Another option, for a more permanent setup, is a water filter (purificador), like the one we use, Rotoplas, or another brand Solo.  Both connect up to the kitchen faucet, and offer carbon-based filters that should be changed every 6 months or so (we don't always do that).  Original cost is around S/100-150, with the replacement filters running around S/50.

It doesn't do much to improve the taste, but we, and other missionaries, have never gotten sick (as far as I know) using this system in Piura, Trujillo, or Lima.  We use this mostly for cooking, washing veggies (just to be safe), and coffee/flavored drinks, since it is more cost effective than bottled water.

For drinking water at home, we have tended to get a "bidon" or big 20 liter bottle delivered to the house.  It runs about S/10 to refill, and around S/35 or so to get the bottle originally (full).  Just find a decent brand, and this will usually taste better than filtered water from the sink.

When at a restaurant, and are offered a "refresco" with a meal, feel free to ask if it was made with boiled water or water from a "bidon".  This is typically true in most locations, but I still usually ask.

Finally, we found that we drink a LOT more than the average Peruvian, even in hot locations like Piura.  Not sure exactly why this is (cost of bottled water/drinks, customs, etc).  But this was an area we decided to not adapt to, and found it important to stay hydrated.